Spring Boot:@Value始终返回null [英] Spring Boot: @Value returns always null

问题描述

我想使用application.properties文件中的值，以便在另一个类的方法中传递它.问题在于该值始终返回NULL.可能是什么问题呢?预先感谢.

I would like to use a value from application.properties file in order to pass it in the method in another class. The problem is that the value returns always NULL. What could be the problem? Thanks in advance.

application.properties

application.properties

filesystem.directory=temp

FileSystem.java

FileSystem.java

@Value("${filesystem.directory}")
private static String directory;

推荐答案

您不能在静态变量上使用@Value.您必须将其标记为非静态，或者在此处查看将值注入静态变量的方法:

You can't use @Value on static variables. You'll have to either mark it as non static or have a look here at a way to inject values into static variables:

https://www.mkyong.com/spring/spring-inject-a-value-to-staticvariables/

以防万一将来链接中断.您可以通过为静态变量设置一个非静态设置器来实现此目的:

Just in case the link breaks in the future. You can do this by making a non static setter for your static variable:

@Component
public class MyComponent {

    private static String directory;

    @Value("${filesystem.directory}")
    public void setDirectory(String value) {
        this.directory = value;
    }
}

该类必须是Spring Bean，否则它将不会被实例化，并且Spring将无法访问setter.

The class needs to be a Spring bean though or else it won't be instantiated and the setter will be not be accessible by Spring.

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